droflohelper.java

一个工作流设计及定义的系统,可以直接与数据库结合进行系统工作流程的定义及应用.

/*
 * Copyright (c) 2005, John Mettraux, OpenWFE.org
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.  
 * 
 * . Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * 
 * . Neither the name of the "OpenWFE" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: DrofloHelper.java,v 1.6 2005/05/17 16:40:20 jmettraux Exp $
 */

//
// DrofloHelper.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.0.04 31.10.2002 John Mettraux ([e-mail])
//

package openwfe.org.droflo;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;

import org.python.core.Py;
import org.python.core.PyObject;
import org.python.util.PythonInterpreter;


/**
 * A singleton to be used by jsp / servlets
 * Now, it's a facade to a jython implementation of the input system
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Date: 2005/05/17 16:40:20 $
 * <br>$Id: DrofloHelper.java,v 1.6 2005/05/17 16:40:20 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public class DrofloHelper
{

    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger
        .getLogger(DrofloHelper.class.getName());

    //
    // CONSTANTS

    public final static String DROFLO_PY 
        = "droflo.py";

    private static DrofloHelper singleton = null;

    //
    // FIELDS

    private String source = null;
    private long sourceLastModified = 0L;
    private PythonInterpreter interpreter;

    //
    // CONSTRUCTORS

    public DrofloHelper (final ServletContext context)
    {
        super();

        this.source = context.getInitParameter(DROFLO_PY);
        this.source = context.getRealPath(source);

        if (this.source == null)
        {
            log.warn
                ("\n========================================================="+
                 "\nParameter '"+DROFLO_PY+"' is missing from WEB-INF/web.xml."+
                 "\nIt is mandatory and indicates where the input.py file"+
                 "\nlies."+
                 "\n=========================================================");
            return;
        }

        log.info("source is "+this.source);

        refresh();
    }

    //
    // METHODS

    public void renderFlow
        (final DrofloSession session,
         final java.io.Writer writer,
         final HttpServletRequest req)
    {
        PyObject method = this.interpreter.get("renderFlow");

        PyObject[] args = new PyObject[3];
        args[0] = Py.java2py(session);
        args[1] = Py.java2py(writer);
        args[2] = Py.java2py(req);
        method.__call__(args);
    }

    public void parseRequest 
        (final DrofloSession session, final HttpServletRequest req)
    {
        PyObject method = this.interpreter.get("parseRequest");

        PyObject[] args = new PyObject[2];
        args[0] = Py.java2py(session);
        args[1] = Py.java2py(req);
        method.__call__(args);
    }

    /**
     * If necessary, reloads the source
     */
    protected void refresh ()
    {
        java.io.File f = new java.io.File(this.source);

        long lastModified = f.lastModified();

        if (this.interpreter == null ||
            lastModified > this.sourceLastModified)
        {
            this.sourceLastModified = lastModified;

            //
            // setup interpreter

            org.python.core.PySystemState.initialize();
            this.interpreter = new org.python.util.PythonInterpreter();
            //this.interpreter.exec("jython = 1");

            // 
            // eval 'input.py'
            
            this.interpreter.execfile(this.source);
        }
    }

    //
    // STATIC METHODS

    public static DrofloHelper getInstance (final ServletContext context)
    {
        if (singleton == null)
            singleton = new DrofloHelper(context);
        singleton.refresh();
        return singleton;
    }

    public static DrofloHelper getInstance (final HttpServletRequest req)
    {
        return getInstance(req.getSession().getServletContext());
    }

}